In this article, I argue that political philosophers like Rawls and Habermas that characterize their methods as non-metaphysical or postmetaphysical depend on constitutions in order to provide a positive and public reference point for democratic participants. Michelman shows how this dependency is problematic, by contending that disagreement about the meaning of constitutional rights and the indeterminacy of their application undermines the rationality of consensus. I argue that his concerns raise serious problems for Rawls’ theory. Habermas, on the other hand, has (...) some tools to deal with Michelman’s critique — namely, his distinction between discourses of justification and application, and his idea of constitutional patriotism — but he must concede that much of the substance of constitutional democracy is basically up for grabs. I conclude by suggesting why these consequences are less threatening than they may seem. (shrink)